The present invention relates to a device to prevent injuries and deaths associated with the main drain of a swimming pool or spa. Pools and spas use a pump to permit the water to circulate both within the spa or pool, through conditioning or heating apparatus and the like, and back to the spa or pool. The point or points from which the pump draws water from the structure, often known as the main drain, can be very dangerous to persons within the structure because of the risks associated with the possibility that a person, or a part of their body might cover, or blind off, that main drain. By covering all or part of that drain, greatly increased suction may result at that point, acting to trap the person. If the person's face is below water at that time, they may drown. Another risk is that of a person (often a child) placing their buttocks over, and covering, the drain. This occurs most frequently on drains where the grate is missing, but may also occur on flat drain covers that can be so covered and collapse with the increased suction. In this case, the greatly increased suction can act to eviscerate the person through their anus, permanently injuring them. Another risk is of a person's hair becoming entangled in a grate, trapping the person next to the drain, resulting in drowning.
Conventional drain systems have used "anti-vortex" covers, which lack holes at the top, preventing or discouraging a person from covering that hole, and which reduce flow rates (to perhaps less than 6 ft./sec.) to reduce turbulence. Covering the drain with a grate, often having 1/2 inch openings, have also been used.
Other conventional drain systems have used dual or multiple main drains, separated by sufficient distance to prevent both from being covered, ideally reducing the pressure should one become covered, or a plumbing design that prevents any single drain becoming connected exclusively to a suction pump. Further ways include gravity-fed collector sumps, and vent stacks, which attempt to limit total suction to about 8 ft.-H.sub.2 O.
One disadvantage of conventional systems is that they often involve extra components, adding complexity and cost to the system. Another disadvantage is that the grates or other covers may fail, permitting a person to cover that drain, and become entrapped, or disemboweled. Another is that even grates designed to be anti-vortex may still permit hair entanglement in the drain cover support attachment points or in the cover openings themselves. Further, it is not clear that multiple drains per pump provide sufficient protection because of the potential for dynamic hydraulic imbalance, which may still permit a large increase in suction at the drain.
Previous drains and suction entrapment devices for pools or spas disclosed in patents include the following:
U.S. Pat. No. 5,734,999 discloses a floor drain grate that including two or three separate regions through which water can flow into the drain. The regions are spaced-apart, preferably one to two feet, to effectively prevent a swimmer from covering all openings simultaneously, preventing suction entrapment. One or more elongate channel portions are used to create a flow passage structure to space apart the inflow regions, and a central portion overlies the drain, and provides a further inflow region. The floor drain grate, including the channel portions, is disclosed as overlying the pool floor. The central portion is disclosed as being securely attached to the drain, using screws, and the channel portions are disclosed as being integrally formed with the central portion, or as being attached thereto using screws or adhesives.
U.S. Pat. No. 3,940,807 discloses an outlet drain for a spa including channels extending radially substantially in all directions from the central drain aperture through which water can enter the drain. The channels extend approximately two feet, from the ends of opposing channels, to effectively prevent a swimmer from covering all of the channels simultaneously, preventing suction entrapment. It also discloses an anti-vortex plate covering the drain sump. The drain is disclosed as being able to be integrally molded with or bonded to the bottom of the pool, or to replace the existing drain in a pool or spa. The vortex plate is disclosed as being held in position by screws, and the retrofittable drain is held in place by spring clips that apply a downward force to provide a secure fit and to prevent unintended removal.
U.S. Pat. No. 4,658,449 discloses an adapter for pool drains that uses an upper ring raised from the surface of the pool floor, and arms radiating downward therefrom to a lower ring, or perimeter frame, that rests on the floor of the pool, to define a raised screening surface above the pool drain. The larger surface area provides a greater area for suction to reduce the suction at any given point. The adapter is also disclosed to use either a heavy metallic mesh or plurality of metallic arms among the radiating arms and the top of the upper ring to reduce the whirlpool effect. The perimeter frame is disclosed as having mounting arms that run across it, intersecting the pool drain, to permit the adapter to be bolted or screwed to the drain.
U.S. Pat. No. 4,121,307 discloses a pool having an open gutter around its perimeter, including therein a suction pipe providing positive withdrawal of water in the gutter. The bottom of the pool is shown to have a main drain utilizing an elongated grate. The grate is not described as being removable.